Lubricating element



Fa. 13, E. s. PATCH LUBRIOATING ELEMENT Filed Oct. 25'. 1937 Rm WE m5 mmm a EM N QM E E my 5 E Q i m m Wm NW Patented Feb. 13, 1940 PATENTOFFICE 1 LUBRIGA'I'ING ELEMENT Earl S. Patch, Dayton, Ohio, assignor toGeneral Motors Corporation, Detroit, Mioln, a corporation of DelawareApplication October .23, 1937, Serial No. 170,527

Claims.

This invention relates to relatively movable, self-lubricating plates ormembers and more particularly to a laminated leaf spring constructionthat is self-lubricating.

In leaf spring constructions it is the usual practice to form theindividual leaves so that when they are assembled the main compressiveload from one leaf to the next is carried adjacent the ends of theleaves. For this reason it is desirable to provide lubrication at thesurfaces of the leaves adjacent the ends thereof to lessen friction andwear therebetween and also to reduce unnecessary noise during the actionof the spring.

In the past, such lubrication has been accomplished in a number of ways,such as providing wear plates having self lubricating properties, whichplates are interposed between the laminations of a leaf spring assemblyadjacent the ends thereof and which plates therefore carry the fullcompressive load present adjacent the end of the associated spring leaf.Such a structure is shown in my Patent No. 2,051,458 filed July 21, 1933and granted August 18, 1936.

I am also aware of spring constructions wherein one or more buttons ofmetal having self-lubrieating properties have been interposed betweenthe laminations of a leaf spring assembly. In this construction theentire compressive load is again carried by the button or buttons.

Since metal having self-lubricating properties is porous, it isdesirable to reduce a compressive load thereon when assembled in a leafspring structure. This is desirable for several reasons, first thelubricating qualities of the metal are greatly enhanced by a high.degree of porosity thereof since such metal can contain more oil orother lubricant per cubic inch. It is apparent that as the degree ofporosity is increased that the compressive strength of the metal iscorrespondingly decreased, therefore in the prior structures hereinnoted it was necessary to use a self-lubricating metal that did not havea high degree of porosity in order to obtain a sufficient compressivestrength to withstand the conditions under which the metal was used.Thus in the prior use of such metals the percentage of oil impregnationwas low and the self-lubricating properties were limited and thereforeit was necessary to use a relatively large area of such metal in orderto obtain satisfactory lubrication. Second, the porous metal has atendency to bumishat the surface thereof when in rubbing engagement witha harder surface. Such burnishing action tends to close the pores at therubbing surface of the metal and thereby reduce the lubricatingqualities of the metal. Here again large areas of metal are required inorder to obtain satisfactory lubrication.

The present invention is an improvement over the prior uses of porousmetal in spring assemblies and contemplates the use of a highly porousmetal impregnated with lubricant. In the present invention very smallareas of porous metal surfaces, preferably porous bronze, are exposed tothe adjacent leaf spring. Such porous metal has a high degree ofporosity and a high percentage of. lubricant impregnation. The previousdifliculties have been obviated by insetting the porous metal plugs orbuttons in the spring leaf so that the surface of the porous metal issubstantially flush with the surface of the spring. Thus, the porousmetal carries only a part of the compressive load on the springproportional to the area of the porous metal and the area of the.rubbing surface. of the spring. Since the 20 compressive load is.reduced, the burnishing action is lessened considerably and morespecificalimpregnation can be obtained. As a direct result the size ofthe plugs or buttons can be reduced, since a reduced size of button dueto the increased porosity thereof carries an equivalent quantity oflubricant as was carried in the larger wear plates of the prior art thatwere relatively dense in structure when compared with the present porousmetal button.

It is therefore an object of the present invention to provide tworelatively movable members disposed in rubbing engagement to each otherwith one or more porous metal plugs inset in the surface of one of themembers and substantially flush with said surface so that the plug orplugs only carry their share of. the compressive load between themembers in proportion to the relative areas of the plug or plugs and therubbing surface of the member in which they are inset.

It is a further object of the present invention to provide a laminatedleaf spring construction with plugs having self-lubricating propertiesadjacent the end of each of the leaves of the spring and substantiallyflush with the surfaces of the leaf and thereby lubricate the spring. Incarrying out the above object it is a further object, in some instancesto rivet the plug to the spring so that the plug has a flush bearingsurface at either end thereof and therefore can be used to lubricate thenext lower and the next higher spring.

It is a still further object to form recesses in one of the springplates; which recesses are filled with lubricant and then closed by aporous metal plug which is pressed therein so as to be substantiallyflush with .the surface of the plate, said lubricant seeping through theporous metal by capillary action to provide lubrication at the surfacethereof.

Further objects and advantages of thepresent invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein a preferred embodiment of of the present invention isclearly shown.

In the drawing: 7

Fig. 1 shows a side view of a conventional leaf spring assembly,including plugs of self-lubricating metal.

Fig. 2 is a bottom view of the spring shown in Fi 1.

Fig. 3 is an enlarged fragmentary view, in section, of two of the springleaves showing the lubricating plugs riveted in place on one of. theleaves.

Fig. 4 is a view similar to Fig. 3 showing another form of plugutilizing a lubricant reservoir, and

Fig. 5 is a view similar to Fig. 3 showing still another form ofself-lubricating plug.

Referring to Fig. l, a conventional type of leaf spring assembly 29 isshown comprising a main leaf 22 having an eye portion 2% on either endthereof adapted to be associated with suitable spring hangers. Aplurality of leaves 26 are associated with the main leaf 22 and are ofgraduated lengths. Hie leaves 28 are tightly bolted to the main leaf 22by a bolt 28 passing through the central portion of all of the leaves.Two straps or clips 30, riveted or otherwise secured to one of theleaves and spaced approximately equi-distant between the center of theleaf spring assembly and the eye portions 24 of the main leaf areprovided to further hold the spring leaves together and moreparticularly to maintain alignment thereof. Each of the leaves 26 isdrilled adjacent either end thereof to provide three holes 32 there-'in. In the present embodiment the holes 32 extend completely through theleaves 26. Porous metal plugs 54 having a head portion at one endthereof are pressed within the holes 32 and are headed at the oppositeend thereof to rivet the same in place. Preferably the holes 32 aresuitably chamfered at either end thereof so that the plugs 3d, whenriveted in place, are substantially flush with the surface of the springleaf 26. The porous metal plugs 34 are preferably formed from porousbronze material but also may be formed from porous copper, nickel oriron alloys or any other suitable porous material. Plugs 84 areimpregnated with oil, or other lubricant, prior to being riveted inplace in the spring leaves. Thus when the spring is assembled, theporous metal plugs 34 are in rubbing engagement with the next longerspring leaf and oil which seeps out of the plug due to capillary actionlubricates the leaves adjacent the ends thereof. In this mannersatisfactory lubrication of a laminated leaf spring 20 is affected andmaintained for long periods of operation.

The plugs 34 being fabricated from metal having a high degree ofporosity are capable of containing lubricant up to 30% or more byvolume, and therefore, may be of relatively small diameter. These smalldiameter plugs do not tend to parent that fewer plugs may be used, forexample, one, if the size thereof is increased slightly. Porous metalsuch as the porous bronze used in the aforementioned plugs can befabricated by several methods, one of which is disclosed in a patent toWilliams et 9.1. 1,642,347, filed August 17, 1922.

The modification shown in Fig. 4 isprovided to include porous metalplugs 38 which are preferably press-fitted into recesses 38 in thespring leaves. The height of a plug 38 is not as great as the depth of arecess 38 and therefore lubricant may first be placed in the recess andthen the plug pressed in place. Thus each plug 36 is provided with asmall reservoir of lubricant which due to the porous nature of. the plugslowly seeps therethrough to lubricate the surface of the plug andthereby lubricate the surface between the spring leaves.

Fig. 5 shows still another embodiment of the present invention wherein aplug MI is employed which has a shoulder portion 02 thereon. The plug dBis pressed into a counterbored hole within the spring leaf so that theshoulder portion 42 is substantially fiush with the surface of thespring leaf. In this embodiment the plug 40 is not riveted in place butis maintained in position by the adjacent spring leaf which bearsthereon. In this modification a larger lubricating surface is provided.

It will be noted that in all of the embodiments shown herein that thelubricating surface of the porous metal plug is substantially flush withthe surface of the associated spring leaf. In this manner the porousmetal is only subjected to that portion of the compressive load upon theleaf as determined at the relative areas of the plug surface and therubbing surface of the spring leaf.

It is to be understood that while the present I I disclosure isdirected, namely, to the lubrication of the leaf spring assemblies thatthe principle thereof can be applied to any two relatively movingsurfaces that are in rubbing engagement with one another. It istherefore within the scope of the present invention to lubricate any tworubbing surfaces wherein the self-lubricating porous metal plugs aresubstantially fiush with one of the surfaces and are only subjected to aproportional part; of the compressive load carried by the surface asdetermined by the relative areas of the surface and the porous metalpart.

It is apparent that in some instances the porous metal plug need not rubagainst the engaging surface but may be out of engagement therewith; asfor example, when the plug carrying member is disposed above the othermember. In this case lubricant seeping out of the plug will flow bygravity to the rubbing surfaces. Obviously, the plug should besubstantially flush with the sur face of the member carrying the samebut does not necessarily have to be disposed so as to actually rub onthe other member.

While the embodiments of the present invention as herein disclosed,constitute preferred forms, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A laminated spring, comprising a plurality of superimposed springplates of graduated lengths and provided with recesses near the endsthereof; a plurality of porous metal, oil impregnated plugs disposed insaid recesses and riveted at either side of the spring plates, thesurfaces of said plugs being substantially flush with the pressive loadon said plates as determined by the relative areas of the plugs on theplates.

2. A laminated spring, comprising a plurality of superimposed springplates of graduated lengths; a plurality of porous bronze oilimpregnated plugs extending through and riveted to said spring platesand disposed with their rubbing surfaces flush with the surfaces of the.respective spring plate, said plugs only carrying a proportional shareof the compressive load as determined by the relative areas of the plugsand the plates.

3. In combination, two superimposed plates adapted to be engageable andrelatively movable with respect to each other; a plurality of recessesin one of said plates; a plurality of porous metal lubricant impregnatedplugs riveted in said recesses so that the outer surfaces of the plugsare flush with the engaging surface of said plate, whereby the engagingsurfaces of the plates are lubricated and the plugs are only subjectedto that portion of the compressive load on said plate as determined bythe relative areas of the plate and the plugs.

4. In combination, two relatively movable members disposed in rubbingcontact with one another, a porous metal plug passing through one ofsaid members, said plug having a head portion disposed to lie flush withone surface of t the said member and being adapted to be riveted over atthe other end thereof so as to be flush with the other side of themember while fixedly secured thereto, said plug carrying only aproportional share of the load between said member as determined by therelative areas of the member and the exposed surface of the plug.

5. In combination, a plurality of superimposed relatively movable platesdisposed in rubbing contact with one another, a porous metal partpassing through one of said plates and fixedly secured thereto bymeansof enlarged diameter portions at both ends thereof which preventremoval of the part from the plate, one of said enlarged diameterportions being substantially flush with the surface of the plate whichis in rubbing contact with an adjacent plate, said porous metal partcarrying only a proportional share of the compressive load between theplates as determined-by the relative areas of exposed porous metalsurface and plate surface.

EARL .S. PATCH.

